Conventionally, metallic pigments have been used for metallic coatings and printing inks, for kneading into plastic, and the like for the purpose of achieving a decorative effect with a focus on metallic feeling. In these applications, coating films obtained by using metallic pigments are often required to have adhesion and chemical resistance such as acid resistance or alkali resistance.
In the field of coatings, in view of resource saving and anti-pollution, there has been an increasing need for conversion to water-based coatings in which the amount of an organic solvent used is small, but there are still few examples of water-based coatings which are practicable in metallic coatings containing a metallic pigment. This is an extremely serious safety problem during production processes of coatings and inks in paint manufacturers and ink manufacturers as well as during processes of coatings and prints in automobile manufacturers, home appliance manufacturers and printing companies. The corrosion resistance of metallic pigments in water, water-based coatings or water-based inks is, hereinafter, referred to as “storage stability”.
Patent Document 1 discloses a metallic pigment containing an amine salt of molybdic acid and covered with a three-dimensionally crosslinked resin in order to simultaneously achieve storage stability as well as adhesion and chemical resistance in water-based coatings or water-based inks. However, the method according to the patent document is insufficient in storage stability.
Patent Document 2 discloses a metallic pigment containing an amine salt of heteropolyacid. However, use of the metallic pigment obtained by the method according to the patent document does not achieve adhesion and chemical resistance such as acid resistance or alkali resistance in a coating film.